THE RELATIONSHIPS BETWEEN NON-INVASIVE EXPLORATIONS IN PULMONARY SARCOIDOSIS OF RECENT ORIGIN, AS SHOWN IN BRONCHOALVEOLAR LAVAGE, SERUM, AND PULMONARY-FUNCTION TESTS

Abstract

To test the validity of noninvasive criteria for staging the activity of sarcoidosis within the alveolar structure, the following investigations were carried out in 35 patients with sarcoidosis: bronchoalveolar lavage (cellular and protein components), serum assays of IgA, IgG and of the activity of the angiotensin-converting enzyme (SACE), and investigation of pulmonary functional parameters. To simplify the interpretation of the measurements, the group studied was strictly limited to nonsmokers with pulmonary sarcoidosis of recent origin. Results were compared to a group of 8 control subjects. The patient group was characterized by a significant increase in total protein and IgG concentrations, IgG/albumin ratio and percentage of lymphocytes in the bronchoalveolar lavage (BAL) fluid. There was a strong correlation in the BAL fluid of patients between the IgG/albumin ratio and the percentage of lymphocytes (r1/2 0.58, P < 0.001), indicating a relationship between the humoral and cellular processes in the alveolar structure of patients with sarcoidosis. Despite the absence of open lung biopsies, the existence of correlation between the percentage of lymphocytes in BAL fluid, previously shown to reflect the activity of the disease, and IgG/albumin ratio in BAL fluid or diffusing capacity adjusted to age and alveolar volume (DLva) suggest that the 2 latter parameters are also dependent on the disease within the alveolar structure in nonsmoking patients with sarcoidosis of recent origin (DLva vs. IgG/albumin ratio: r = -0.72, P < 0.001 and DLva vs. percent of lymphocytes: r = -0.42, P < 0.02). The practical interest of DLva measurement is limited by certain restrictive conditions (sarcoidosis of recent origin, nonsmoking subjects). The other functional parameters (static volumes, FEV1IVC [1 s forced respiratory volume/vital capacity] and retraction coefficient) are not related to any cytological or biochemical component of BAL fluid. A significant relationship exists beween the percentage of lymphocytes in BAL fluid and the serum IgG concentration (r = 0.63, P < 0.001). This might result from enhanced pulmonary production of IgG under the influence of T lymphocytes. This fact is of practical interest because of the steep slope of the relationship and of the noninvasive character of the sampling for serum IgG determination. IgA concentration in the serum and in BAL fluid and the SACE were not correlated by any of the other parameters.